Method and apparatus for forming bulbular base piles

ABSTRACT

A BOREHOLE FORMING TOOL OR DRIVE PIPE IS PROVIDED WITH AN EJECTION CHAMBER AT ONE END WITH MEANS FOR CONNECTING THE TOOL TO A SONIC DRIVING HEAD. A SONIC DRIVING HEAD IS PROVIDED WITH A DRIVING MANDREL WHICH IS CONSTRUCTED TO TELESCOPICALLY RECEIVE THE TOOL AND ADAPTED TO DRIVINGLY ENGAGE THE DRIVE PIPE IN ONE POSITION AND ENGAGE A PISTON IN THE EJECTION CHAMBER OF THE PIPE IN A SECOND POSITION. THE EJECTION IS FILLED WITH A CHARGE OF SOLIDIFIABLE MATERIAL SUCH AS CEMENT AND THEN DRIVEN SONICALLY TO THE DESIRED DEPTH IN AN EARTH FORMATION, THE MANDREL IS THEN ROTATED TO ENGAGE THE PISTON AND THE CHARGE OF MATERIAL THEN SONICALLY EJECTED FROM THE CHAMBER AND INTO THE FORM OF A RADIALLY-EXTENSIBLE MASS IN THE FORMATION.

March 9, 1971 F. R. STIFLER, JR

METHOD AND APPARATUS FOR FORMING BULBULAR BASE FILES Filed Aug. 8, 1968 FIG.3

INVENTORI FELIX RAYSTON STIFLER,JR.

8Y1? Z fiua HIS ATTORNEY United States Patent Oflice US. Cl. 61-53.6 4 Claims ABSTRACT OF THE DISCLOSURE A borehole forming tool or drive pipe is provided with an ejection chamber at one end and with means for connecting the tool to a sonic driving head. A sonic driving head is provided with a driving mandrel which is constructed to telescopically receive the tool and adapted to drivin-gly engage the drive pipe in one position and engage a piston in the ejection chamber of the pipe in a second position. The ejection is filled with a charge of solidifiable material such as cement and then driven sonically to the desired depth in an earth formation, the mandrel is then rotated to engage the piston and the charge of material then sonically ejected from the chamber and into the form of a radially-extensible mass in the formation.

BACKGROUND OF THE INVENTION Field of the invention In the construction of buildings, bridges, piers, drilling platforms and other similar structures, it is essential that a solid, stable foundation be established on which to rest the structure. Such foundations are generally established by placing a number of piles into the earth on which to rest the structure. The load capacity of these piles depend upon such factors as soil conditions and size, shape and length of pile. The resistance of a pile to displacement in an earth formation is provided by the friction along the length of the pile and on tip resistance. In some soils very little shaft resistance is encountered in which case, tip or end resistance must carry the entire load.

The present invention relates to the construction in place of bulbular base concrete piles and pertains more particularly to a method and apparatus for the forming in place of concrete end-bearing piles having a large bulbular base or foot.

The type of soil into which the pile is driven has an important bearing upon its load carrying capacity. For example, piles which are sunk into clay type soils carry most of the applied load by soil friction along their shaft length. Very little resistance is supplied by the tip. On the other hand, piles which are placed into a sandy type of formation carry most of the applied load by tip resistance when the load acts downward, and very little of the load is carried by soil friction along the shaft.

It has been found that an ideal shape for an end or tip-bearing pile would be one having a large or bulbous base or foot, and a normal or regular sized shaft. Such a shape for such piles would offer great savings in material in that the length and diameter of the shaft of such a pile would be much less than for a pile of constant diameter having the same load carrying capacity.

Description of prior art Various methods are known for constructing bulbular or large based piles. Perhaps the better known method is the Franki method. In accordance with this method a specially constructed rig is moved to the construction site. A casing or heavy guage, high-tensile alloy steel is raised in place. A portion of very dry concrete is then placed in the bottom of the casing to form a driving 3,568,452 Patented Mar. 9, 1971 plug. Next, a heavy, solid ram weighing from two to four tons is lowered into the casing and raised and dropped to drive the plug into the ground which pulls or carries the casing with it by means of friction between it and the casing. At the desired level the casing is then anchored to the rig and the plug driven out the bottom of casing. More concrete is then dumped into the casing and rammed out the bottom of the casing to form the bulb. The casing is then raised small increments as more concrete is dumped into the casing and rammed out the bottom to form the rest of the pile.

Among the disadvantages of the prior known methods of constructing such bulbular base piles is that the steps are long and slow and require heavy and cumbersome equipment. Such methods are time consuming and therefore expensive.

Furthermore, the apparatus used being heavy, complicated and cumbersome, is also expensive.

SUMMARY OF THE INVENTION It is therefore the primary object of the present invention to overcome the above and other disadvantages of such prior methods and apparatus by providing a method and apparatus that is rapid and efficient for the construction in place of high load capacity piles.

It is a further object of the present invention to provide a method that is simple, easy to use and rapid in the formation in place of high load capacity piles.

Still another object of the present invention is to provide a method of forming bulbular base piles that utilizes a sonic driving head as power means for forming the bulbular base.

A further object of the present invention is to provide a method of forming bulbular based piles that takes advantage of the power and efficiency of a sonic driving head to form the borehole and the bulbular base for the pile.

Still a further object of the present invention is to provide a method of forming bulbular base piles that takes maximum advantage of the various load carrying capacities of the various strata in an earth formation.

BRIEF DESCRIPTION OF THE DRAWING The above and other objects and advantages will become apparent from the following description illustrating a preferred embodiment of the invention when read in connection with the accompanying drawings in which:

FIG. 1 is a diagrammatic view taken partially in section showing the apparatus of the present invention imbeded to a predetermined depth in an earth formation.

FIG. 2 is a diagrammatic view of the apparatus of the present invention in the process of forming the bulbular base of the pile.

FIG. 3 is a diagrammatic view partially in section showing the base for the pile formed and the apparatus being withdrawn from the borehole while the shaft of the pile is being formed.

FIG. 4 is a section through 4-4 of FIG. 1 of the apparatus.

FIG. 5 is a sectional view of a modification of the driving mandrel.

DESCRIPTION OF PREFERRED EMBODIMENT Referring to FIGS. 1-4, a preferred embodiment of the apparatus is illustrated. As seen in FIGS. 1-4, the apparatus comprises a borehole forming tool 11 in the form of an elongated tubular member, pipe or casing section 12 having a driving cap or plug 13 closing the lower or driven end thereof to form an ejection chamber. The tubular member 12 has stop means in the form of lugs 14 and 15 affixed to the inner wall and spaced from the lower end thereof. A piston or plug member 16 is slidably received in the lower end of the tubular member between the stop means and plug means 13, thus forming a variable volume chamber, the function of which will be more fully explained hereinbelow.

The driving apparatus comprises a sonic vibratory driving head 17 supported by suitable means such as a cable 18 and a suitable derrick or crane structure (not shown). The driving head 17 is coupled by swivel coupling 19 to an elongated driving mandrel 20 having a central bore 21 therethrough forming a conduit in communication with conduit 22 leading from a suitable source (not shown) of fluid solidifiable material such as cement or concrete. The driving mandrel 20 extends into the tubular member 12 and engages the stops or lugs 14 and to form a driv ing connection therebetween. Spacers 23 and 24 may be provided between members 12 and to the members with respect to one another. The mandrel 20 is provided with slots 25 and 26 therein for receiving lugs 14 and 15 and permitting the mandrel to slide past lugs 14 and 15 when rotated 180 and engage plug or piston member 16. This construction permits the driving mandrel to engage the piston member 13 and drive it downwardly and out the bottom of the tubular member 12 as shown in FIGS. 2 and 3.

The aforementioned connection between the mandrel and the bore tool may be reversed. That is, the lugs may be formed on the mandrel and a slotted sleeve be attached to the interior of the bore tool. The driving mandrel may also be connected to the bore tool by means of a bayonet connection or suitable clamp means (not shown). Such a connection would offer a more positive connection between the members.

An alternate form of the piston means which serves as the upper wall of the chamber is shown in FIG. 5. This arrangement eliminates the need of the piston or plug member 16 and also eliminates the need of charging or filling the ejection chamber before the bore-forming tool or drive pipe is driven. In this embodiment the lower end of the driving mandrel 20 is closed off such as by a wall member 28. The wall member 28 has a central opening pointing up therethrough which may be closed off such as by a check valve 30. The check valve 30 as illustrated comprises a spherical member 31 which is floatingly retained in a cage 32. Valve 30 is responsive to pressure from below to move member 31 into engagement with the seat 29a of opening 29 to restrict the flow of material therethrough in the upward direction. When subjected to pressure from above, the spherical member 31 will unseat or disengage from the seat 29a and permit free fiow of material through the opening 29. Slots 33 and 34 formed in the driving mandrel 25 are provided to permit passage of stop means or lugs 14 and 15. These slots do not extend completely through the walls of the mandrel 20.

Suitable means may be provided for retrieving the boreforming tool or drive pipe. Any suitable means may be provided for this purpose, such as clamp means 35. Clamp means 35 comprises backup mandrel 36 extending downward along the body of the driving mandrel 20. A skirt 37 extends downward parallel to the fixed mandrel in spaced relationship thereto to form an annular space 38 into which the end of the drive pipe may be received. A number of screws 39 which extend through this skirt 37 and into the annular space 38 are spaced circumferentially around the skirt 37. These said screws 39 extend into engagement with the drive pipe or tubular member 12 forcing it into tight engagement with the fixed mandrel 36, thus providing a tight driving engagement or connection between the driving mandrel 20 and the drive pipe 12. The clamp means 35 is rigidly connected to the driving mandrel 20 in any suitable manner such as by welding or by brazing.

OPERATION In forming a bulbular base pile with the above described apparatus, the piston 16 is placed in the lower end of tubular member 12 against stops 14 and 15. This forms a chamber in which a batch or charge of suitable solidifiable material such as cement or concrete is placed and the lower end is then closed oif by plug 13. The bore forming tool is then vertically positioned in place and the driving mandrel 20 is then inserted into the tool and against the stops 14 and 15 or otherwise connected to tubular member 12. The driving head 17 is started and lowered with the mandrel 20 as it drives the tool or drive pipe 11 into the earth formation. When the tool reaches the desired depth, the driving is halted and driving mandrel rotated the necessary amount, say so that lugs 14 and 15 engage slots 25 and 26 and the mandrel slides past the stops and into engagement with piston 16. The driving action of the head 17 and mandrel 20 is again renewed and the piston 16 driven out the end of member 12 forcing ahead of it the batch or charge of cement 27 and cap 13. The cement charge, as it is driven out the end of the tubular member 12, forces the surrounding earth formation radially outwardly forming an enlarged radiallyextensible or bulbular base or footing for the pile, as shown in FIG. 2. After the bulbular base is formed for the pile, the driving mandrel 20 and tubular member 12 are clamped together and more concrete or cement in the fluid state is pumped through conduit 22 and bore 21 of the mandrel 20 to fill the borehole and form the shaft of the pile as the driving apparatus and tubular member 12 is vibrated and hoisted or lifted from the borehole, as shown in FIG. 3. The apparatus is then ready to be moved into position for forming the next pile.

The modification of the driving mandrel 35 illustrated in FIG. 5 greatly simplifies the above-described operation by eliminating the necessity of using the plug or piston means 16 and also eliminating the necessity of filling the ejection chamber with a charge of the soidifiable material before driving the tubular member 12 into the earth formation.

The present invention is not intended to be limited to the foregoing illustrative embodiments, as it can be readily seen that various changes may be made in the invention without departing from the intended spirit and scope of the invention as defined by the appended claims.

I claim as my invention:

1. A method of forming a bulbular based pile comprising the steps of:

providing an elongated pile-forming member having an axial bore therein with piston means to form a chamber in the lower end thereof when said end is closed;

placing a fluid mixture of solidifiable material in said chamber;

closing said lower end of said member;

sonically forcing said lower end of said member into an earth formation to a desired level to thereby form a borehole in said formation;

providing a sonic driver having a portion thereof adapted to extend into said tubular member and drivingly engage the upper end of said chamber;

inserting said portion into said tubular member and into driving engagement with the upper end of said chamher; and,

sonically forcing said solidifiable material out of said chamber and into the form of a mass of enlarged diameter in said formation.

2. The method of claim 1 including the step of:

limiting the travel of said piston means within said chamber;

providing said extending means with means to engage said tubular member when in a first position of adjustment and to engage said piston means when in a second position of adjustment.

3. Apparatus for the formation in place of bulbular base piles comprising:

a sonic vibratory driving head;

an elongated driving mandrel attached to said driving head;

a plurality of slots extending partially along said mandrel;

conduit means communicating with one end of said driving mandrel and a point adjacent said driving head;

a bore-forming tool telescopically received on said driving mandrel;

a plurality of lugs extending inward from said boreforming tool and adapted to be received in said slots;

a variable volume chamber in one end of said tool;

reciprcable piston means forming an upper wall for said chamber;

said driving mandrel engaging said lugs for driving said bore-forming tool in one angle adjustment with respect to said tool and said mandrel by-passing said lugs for driving said upper wall of said chamber in a second angle of adjustment.

4. The apparatus of claim 3 wherein: the lower end of said driving mandrel forms said piston means.

References Cited UNITED STATES PATENTS 2,184,514 12/1939 Cleesattel 6153.62X 3,187,513 6/1965 Guild 6l-53.6X 3,423,944 1/1969 Goodman 6l-5 3.6

FOREIGN PATENTS 265,778 3/ 1950 Switzerland.

JACOB SHAPIRO, Primary Examiner US. Cl. X.R. 

